Diurnal patterns of ruminal concentrations and portal appearance rates of short-chain fatty acids in sheep fed a hay or a concentrate/straw diet in two meals daily
Kristensen, N.B.; Danfaer, A.; Agergaard, N.
Acta Agriculturae Scandinavica Section A Animal Science 46(4): 227-238
1996
ISSN/ISBN: 0906-4702 DOI: 10.1080/09064709609415875
Accession: 002805023
Three rumen fistulated and catheterized sheep were meal-fed and used to study ruminal and arterial concentrations of short-chain fatty acids (SCFA) as well as portal appearance rates of SCFA and irreversible loss rate (ILR) of acetate in 24 h periods on a hay and a concentrate/straw diet, respectively. Ruminal and arterial concentrations as well as portal appearance rates of SCFA and ILR of acetate were significantly affected by the intake of feed. Generally, the highest concentrations and appearance rates were obtained 2 h after feeding. The portal recovery of arterial acetate was not affected by feeding or diet. The 24 h means were 0.68 +- 0.01 and 0.67 +- 0.01 on the hay and the concentrate/straw diet, respectively. Partial correlation coefficients corrected for the effects of time, sheep, and diet were calculated for the relationships evaluated. The portal appearance rate of acetate (r = 0.52, P lt 0.001) and the portal net appearance rate of propionate (r = 0.68, P lt 0.001) were linearly related to the ruminal concentrations of the two SCFA. The logarithm of the portal net appearance rate of butyrate seemed to be linearly related to the logarithm of the ruminal concentration of undissociated butyric acid (r = 0.70, P lt 0.001) when the effect of time was omitted from the model. The portal appearance rate of acetate (r = 0.22, P lt 0.05) and the portal net appearance rate of propionate (r = 0.63, P lt 0.001) as well as butyrate (r = 0.55, P lt 0.001) were linearly related to the arterial concentration of the respective SCFA. The results show that within animal and diet the ruminal as well as arterial concentrations are good predictors of SCFA portal appearance rates in sheep fed roughage at maintenance. Ruminal and arterial concentrations of SCFA seem less reliable predictors of portal appearance rates of SCFA between diets and sheep.